A common complaint of early polling scolds is that trying to figure out who's going to win each party's nomination at this point is like trying to figure out where in Japan you'll make shore after pushing off from the California coast on a raft. That's a slight exaggeration, because ocean currents are more predictable than polls.
We, meaning me, are of the opinion that early polls still offer insight into the electorate and themes that we'll see play out over the next 12 months, as well as having the side benefit of being fun to explore. Granted, it can be slow and you can make too much out of little things, but, then, I also like to watch baseball.
Anyway! The scolds do have a point. At any given moment in the four most recent contested nomination processes, the person who was leading didn't always turn out to be the nominee. Often didn't. To make that point, we pulled daily data from Real Clear Politics' polling average in 2008 and 2012 and all polling data from Gallup's 2004 surveys to put together a look at the state of play in each contest on this date.
Or, to cut to the chase:
If you're viewing this on Wednesday, August 19, 2015, you'll note that the first Gallup poll isn't yet out. The person who will be leading in it? Joseph Lieberman. He is one of 15 people who held a lead a some point in those four races.
As we and the scolds said: Not predictive. But not un-fun.